MINOR: ebtree: implement the scope-aware functions for eb32
A new kind of tree nodes is currently being developed in ebtree v7,
consisting in storing a scope in each node indicating a visibility
mask so that certain nodes are not reported on certain lookups. The
initial goal was to make this usable with a multi-thread scheduler.
Since the ebtree v7 code is completely different from v6, this patch
instead copies the minimally required functions from eb32 and ebtree
and calls them "eb32sc_*". At the moment the scope is not implemented,
it's only passed in arguments.
diff --git a/ebtree/eb32sctree.c b/ebtree/eb32sctree.c
new file mode 100644
index 0000000..1bb7ca7
--- /dev/null
+++ b/ebtree/eb32sctree.c
@@ -0,0 +1,378 @@
+/*
+ * Elastic Binary Trees - exported functions for operations on 32bit nodes.
+ * Version 6.0.6 with backports from v7-dev
+ * (C) 2002-2011 - Willy Tarreau <w@1wt.eu>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/* Consult eb32sctree.h for more details about those functions */
+
+#include "eb32sctree.h"
+
+
+/* This function is used to build a tree of duplicates by adding a new node to
+ * a subtree of at least 2 entries.
+ */
+REGPRM1 struct eb32sc_node *eb32sc_insert_dup(struct eb_node *sub, struct eb_node *new, unsigned long scope)
+{
+ struct eb_node *head = sub;
+ eb_troot_t *new_left = eb_dotag(&new->branches, EB_LEFT);
+ eb_troot_t *new_rght = eb_dotag(&new->branches, EB_RGHT);
+ eb_troot_t *new_leaf = eb_dotag(&new->branches, EB_LEAF);
+
+ /* first, identify the deepest hole on the right branch */
+ while (eb_gettag(head->branches.b[EB_RGHT]) != EB_LEAF) {
+ struct eb_node *last = head;
+ head = container_of(eb_untag(head->branches.b[EB_RGHT], EB_NODE),
+ struct eb_node, branches);
+ if (head->bit > last->bit + 1)
+ sub = head; /* there's a hole here */
+ }
+
+ /* Here we have a leaf attached to (head)->b[EB_RGHT] */
+ if (head->bit < -1) {
+ /* A hole exists just before the leaf, we insert there */
+ new->bit = -1;
+ sub = container_of(eb_untag(head->branches.b[EB_RGHT], EB_LEAF),
+ struct eb_node, branches);
+ head->branches.b[EB_RGHT] = eb_dotag(&new->branches, EB_NODE);
+
+ new->node_p = sub->leaf_p;
+ new->leaf_p = new_rght;
+ sub->leaf_p = new_left;
+ new->branches.b[EB_LEFT] = eb_dotag(&sub->branches, EB_LEAF);
+ new->branches.b[EB_RGHT] = new_leaf;
+ return container_of(new, struct eb32sc_node, node);
+ } else {
+ int side;
+ /* No hole was found before a leaf. We have to insert above
+ * <sub>. Note that we cannot be certain that <sub> is attached
+ * to the right of its parent, as this is only true if <sub>
+ * is inside the dup tree, not at the head.
+ */
+ new->bit = sub->bit - 1; /* install at the lowest level */
+ side = eb_gettag(sub->node_p);
+ head = container_of(eb_untag(sub->node_p, side), struct eb_node, branches);
+ head->branches.b[side] = eb_dotag(&new->branches, EB_NODE);
+
+ new->node_p = sub->node_p;
+ new->leaf_p = new_rght;
+ sub->node_p = new_left;
+ new->branches.b[EB_LEFT] = eb_dotag(&sub->branches, EB_NODE);
+ new->branches.b[EB_RGHT] = new_leaf;
+ return container_of(new, struct eb32sc_node, node);
+ }
+}
+
+/* Insert eb32sc_node <new> into subtree starting at node root <root>. Only
+ * new->key needs be set with the key. The eb32sc_node is returned. This
+ * implementation does NOT support unique trees.
+ */
+REGPRM2 struct eb32sc_node *eb32sc_insert(struct eb_root *root, struct eb32sc_node *new, unsigned long scope)
+{
+ struct eb32sc_node *old;
+ unsigned int side;
+ eb_troot_t *troot, **up_ptr;
+ u32 newkey; /* caching the key saves approximately one cycle */
+ eb_troot_t *new_left, *new_rght;
+ eb_troot_t *new_leaf;
+ int old_node_bit;
+
+ side = EB_LEFT;
+ troot = root->b[EB_LEFT];
+ if (unlikely(troot == NULL)) {
+ /* Tree is empty, insert the leaf part below the left branch */
+ root->b[EB_LEFT] = eb_dotag(&new->node.branches, EB_LEAF);
+ new->node.leaf_p = eb_dotag(root, EB_LEFT);
+ new->node.node_p = NULL; /* node part unused */
+ return new;
+ }
+
+ /* The tree descent is fairly easy :
+ * - first, check if we have reached a leaf node
+ * - second, check if we have gone too far
+ * - third, reiterate
+ * Everywhere, we use <new> for the node node we are inserting, <root>
+ * for the node we attach it to, and <old> for the node we are
+ * displacing below <new>. <troot> will always point to the future node
+ * (tagged with its type). <side> carries the side the node <new> is
+ * attached to below its parent, which is also where previous node
+ * was attached. <newkey> carries the key being inserted.
+ */
+ newkey = new->key;
+
+ while (1) {
+ if (eb_gettag(troot) == EB_LEAF) {
+ /* insert above a leaf */
+ old = container_of(eb_untag(troot, EB_LEAF),
+ struct eb32sc_node, node.branches);
+ new->node.node_p = old->node.leaf_p;
+ up_ptr = &old->node.leaf_p;
+ break;
+ }
+
+ /* OK we're walking down this link */
+ old = container_of(eb_untag(troot, EB_NODE),
+ struct eb32sc_node, node.branches);
+ old_node_bit = old->node.bit;
+
+ /* Stop going down when we don't have common bits anymore. We
+ * also stop in front of a duplicates tree because it means we
+ * have to insert above.
+ */
+
+ if ((old_node_bit < 0) || /* we're above a duplicate tree, stop here */
+ (((new->key ^ old->key) >> old_node_bit) >= EB_NODE_BRANCHES)) {
+ /* The tree did not contain the key, so we insert <new> before the node
+ * <old>, and set ->bit to designate the lowest bit position in <new>
+ * which applies to ->branches.b[].
+ */
+ new->node.node_p = old->node.node_p;
+ up_ptr = &old->node.node_p;
+ break;
+ }
+
+ /* walk down */
+ root = &old->node.branches;
+ side = (newkey >> old_node_bit) & EB_NODE_BRANCH_MASK;
+ troot = root->b[side];
+ }
+
+ new_left = eb_dotag(&new->node.branches, EB_LEFT);
+ new_rght = eb_dotag(&new->node.branches, EB_RGHT);
+ new_leaf = eb_dotag(&new->node.branches, EB_LEAF);
+
+ /* We need the common higher bits between new->key and old->key.
+ * What differences are there between new->key and the node here ?
+ * NOTE that bit(new) is always < bit(root) because highest
+ * bit of new->key and old->key are identical here (otherwise they
+ * would sit on different branches).
+ */
+
+ // note that if EB_NODE_BITS > 1, we should check that it's still >= 0
+ new->node.bit = flsnz(new->key ^ old->key) - EB_NODE_BITS;
+
+ if (new->key == old->key) {
+ new->node.bit = -1; /* mark as new dup tree, just in case */
+
+ if (eb_gettag(troot) != EB_LEAF) {
+ /* there was already a dup tree below */
+ return eb32sc_insert_dup(&old->node, &new->node, scope);
+ }
+ /* otherwise fall through */
+ }
+
+ if (new->key >= old->key) {
+ new->node.branches.b[EB_LEFT] = troot;
+ new->node.branches.b[EB_RGHT] = new_leaf;
+ new->node.leaf_p = new_rght;
+ *up_ptr = new_left;
+ }
+ else {
+ new->node.branches.b[EB_LEFT] = new_leaf;
+ new->node.branches.b[EB_RGHT] = troot;
+ new->node.leaf_p = new_left;
+ *up_ptr = new_rght;
+ }
+
+ /* Ok, now we are inserting <new> between <root> and <old>. <old>'s
+ * parent is already set to <new>, and the <root>'s branch is still in
+ * <side>. Update the root's leaf till we have it. Note that we can also
+ * find the side by checking the side of new->node.node_p.
+ */
+
+ root->b[side] = eb_dotag(&new->node.branches, EB_NODE);
+ return new;
+}
+
+/*
+ * Find the first occurrence of the lowest key in the tree <root>, which is
+ * equal to or greater than <x>. NULL is returned is no key matches.
+ */
+REGPRM2 struct eb32sc_node *eb32sc_lookup_ge(struct eb_root *root, u32 x, unsigned long scope)
+{
+ struct eb32sc_node *node;
+ eb_troot_t *troot;
+
+ troot = root->b[EB_LEFT];
+ if (unlikely(troot == NULL))
+ return NULL;
+
+ while (1) {
+ if ((eb_gettag(troot) == EB_LEAF)) {
+ /* We reached a leaf, which means that the whole upper
+ * parts were common. We will return either the current
+ * node or its next one if the former is too small.
+ */
+ node = container_of(eb_untag(troot, EB_LEAF),
+ struct eb32sc_node, node.branches);
+ if (node->key >= x)
+ return node;
+ /* return next */
+ troot = node->node.leaf_p;
+ break;
+ }
+ node = container_of(eb_untag(troot, EB_NODE),
+ struct eb32sc_node, node.branches);
+
+ if (node->node.bit < 0) {
+ /* We're at the top of a dup tree. Either we got a
+ * matching value and we return the leftmost node, or
+ * we don't and we skip the whole subtree to return the
+ * next node after the subtree. Note that since we're
+ * at the top of the dup tree, we can simply return the
+ * next node without first trying to escape from the
+ * tree.
+ */
+ if (node->key >= x) {
+ troot = node->node.branches.b[EB_LEFT];
+ while (eb_gettag(troot) != EB_LEAF)
+ troot = (eb_untag(troot, EB_NODE))->b[EB_LEFT];
+ return container_of(eb_untag(troot, EB_LEAF),
+ struct eb32sc_node, node.branches);
+ }
+ /* return next */
+ troot = node->node.node_p;
+ break;
+ }
+
+ if (((x ^ node->key) >> node->node.bit) >= EB_NODE_BRANCHES) {
+ /* No more common bits at all. Either this node is too
+ * large and we need to get its lowest value, or it is too
+ * small, and we need to get the next value.
+ */
+ if ((node->key >> node->node.bit) > (x >> node->node.bit)) {
+ troot = node->node.branches.b[EB_LEFT];
+ return eb32sc_walk_down(troot, EB_LEFT, scope);
+ }
+
+ /* Further values will be too low here, so return the next
+ * unique node (if it exists).
+ */
+ troot = node->node.node_p;
+ break;
+ }
+ troot = node->node.branches.b[(x >> node->node.bit) & EB_NODE_BRANCH_MASK];
+ }
+
+ /* If we get here, it means we want to report next node after the
+ * current one which is not below. <troot> is already initialised
+ * to the parent's branches.
+ */
+ while (eb_gettag(troot) != EB_LEFT)
+ /* Walking up from right branch, so we cannot be below root */
+ troot = (eb_root_to_node(eb_untag(troot, EB_RGHT)))->node_p;
+
+ /* Note that <troot> cannot be NULL at this stage */
+ troot = (eb_untag(troot, EB_LEFT))->b[EB_RGHT];
+ if (eb_clrtag(troot) == NULL)
+ return NULL;
+
+ return eb32sc_walk_down(troot, EB_LEFT, scope);
+}
+
+/* Removes a leaf node from the tree if it was still in it. Marks the node
+ * as unlinked.
+ */
+void eb32sc_delete(struct eb32sc_node *eb32)
+{
+ struct eb_node *node = &eb32->node;
+ unsigned int pside, gpside, sibtype;
+ struct eb_node *parent;
+ struct eb_root *gparent;
+
+ if (!node->leaf_p)
+ return;
+
+ /* we need the parent, our side, and the grand parent */
+ pside = eb_gettag(node->leaf_p);
+ parent = eb_root_to_node(eb_untag(node->leaf_p, pside));
+
+ /* We likely have to release the parent link, unless it's the root,
+ * in which case we only set our branch to NULL. Note that we can
+ * only be attached to the root by its left branch.
+ */
+
+ if (eb_clrtag(parent->branches.b[EB_RGHT]) == NULL) {
+ /* we're just below the root, it's trivial. */
+ parent->branches.b[EB_LEFT] = NULL;
+ goto delete_unlink;
+ }
+
+ /* To release our parent, we have to identify our sibling, and reparent
+ * it directly to/from the grand parent. Note that the sibling can
+ * either be a link or a leaf.
+ */
+
+ gpside = eb_gettag(parent->node_p);
+ gparent = eb_untag(parent->node_p, gpside);
+
+ gparent->b[gpside] = parent->branches.b[!pside];
+ sibtype = eb_gettag(gparent->b[gpside]);
+
+ if (sibtype == EB_LEAF) {
+ eb_root_to_node(eb_untag(gparent->b[gpside], EB_LEAF))->leaf_p =
+ eb_dotag(gparent, gpside);
+ } else {
+ eb_root_to_node(eb_untag(gparent->b[gpside], EB_NODE))->node_p =
+ eb_dotag(gparent, gpside);
+ }
+ /* Mark the parent unused. Note that we do not check if the parent is
+ * our own node, but that's not a problem because if it is, it will be
+ * marked unused at the same time, which we'll use below to know we can
+ * safely remove it.
+ */
+ parent->node_p = NULL;
+
+ /* The parent node has been detached, and is currently unused. It may
+ * belong to another node, so we cannot remove it that way. Also, our
+ * own node part might still be used. so we can use this spare node
+ * to replace ours if needed.
+ */
+
+ /* If our link part is unused, we can safely exit now */
+ if (!node->node_p)
+ goto delete_unlink;
+
+ /* From now on, <node> and <parent> are necessarily different, and the
+ * <node>'s node part is in use. By definition, <parent> is at least
+ * below <node>, so keeping its key for the bit string is OK.
+ */
+
+ parent->node_p = node->node_p;
+ parent->branches = node->branches;
+ parent->bit = node->bit;
+
+ /* We must now update the new node's parent... */
+ gpside = eb_gettag(parent->node_p);
+ gparent = eb_untag(parent->node_p, gpside);
+ gparent->b[gpside] = eb_dotag(&parent->branches, EB_NODE);
+
+ /* ... and its branches */
+ for (pside = 0; pside <= 1; pside++) {
+ if (eb_gettag(parent->branches.b[pside]) == EB_NODE) {
+ eb_root_to_node(eb_untag(parent->branches.b[pside], EB_NODE))->node_p =
+ eb_dotag(&parent->branches, pside);
+ } else {
+ eb_root_to_node(eb_untag(parent->branches.b[pside], EB_LEAF))->leaf_p =
+ eb_dotag(&parent->branches, pside);
+ }
+ }
+ delete_unlink:
+ /* Now the node has been completely unlinked */
+ node->leaf_p = NULL;
+ return; /* tree is not empty yet */
+}
diff --git a/ebtree/eb32sctree.h b/ebtree/eb32sctree.h
new file mode 100644
index 0000000..df97353
--- /dev/null
+++ b/ebtree/eb32sctree.h
@@ -0,0 +1,99 @@
+/*
+ * Elastic Binary Trees - macros and structures for operations on 32bit nodes.
+ * Version 6.0.6 with backports from v7-dev
+ * (C) 2002-2017 - Willy Tarreau <w@1wt.eu>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation, version 2.1
+ * exclusively.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef _EB32SCTREE_H
+#define _EB32SCTREE_H
+
+#include "ebtree.h"
+
+
+/* Return the structure of type <type> whose member <member> points to <ptr> */
+#define eb32sc_entry(ptr, type, member) container_of(ptr, type, member)
+
+/* These types may sometimes already be defined */
+typedef unsigned int u32;
+typedef signed int s32;
+
+/* This structure carries a node, a leaf, a scope, and a key. It must start
+ * with the eb_node so that it can be cast into an eb_node. We could also
+ * have put some sort of transparent union here to reduce the indirection
+ * level, but the fact is, the end user is not meant to manipulate internals,
+ * so this is pointless.
+ */
+struct eb32sc_node {
+ struct eb_node node; /* the tree node, must be at the beginning */
+ unsigned long node_s; /* visibility of this node's branches */
+ unsigned long leaf_s; /* visibility of this node's leaf */
+ u32 key;
+};
+
+/*
+ * Exported functions and macros.
+ * Many of them are always inlined because they are extremely small, and
+ * are generally called at most once or twice in a program.
+ */
+
+/*
+ * The following functions are not inlined by default. They are declared
+ * in eb32sctree.c, which simply relies on their inline version.
+ */
+REGPRM2 struct eb32sc_node *eb32sc_lookup_ge(struct eb_root *root, u32 x, unsigned long scope);
+REGPRM2 struct eb32sc_node *eb32sc_insert(struct eb_root *root, struct eb32sc_node *new, unsigned long scope);
+void eb32sc_delete(struct eb32sc_node *node);
+
+/* Walks down starting at root pointer <start>, and always walking on side
+ * <side>. It either returns the node hosting the first leaf on that side,
+ * or NULL if no leaf is found. <start> may either be NULL or a branch pointer.
+ * The pointer to the leaf (or NULL) is returned.
+ */
+static inline struct eb32sc_node *eb32sc_walk_down(eb_troot_t *start, unsigned int side, unsigned long scope)
+{
+ /* A NULL pointer on an empty tree root will be returned as-is */
+ while (eb_gettag(start) == EB_NODE)
+ start = (eb_untag(start, EB_NODE))->b[side];
+ /* NULL is left untouched (root==eb_node, EB_LEAF==0) */
+ return eb32sc_entry(eb_root_to_node(eb_untag(start, EB_LEAF)), struct eb32sc_node, node);
+}
+
+/* Return next node in the tree, or NULL if none */
+static inline struct eb32sc_node *eb32sc_next(struct eb32sc_node *eb32, unsigned long scope)
+{
+ struct eb_node *node = &eb32->node;
+ eb_troot_t *t = node->leaf_p;
+
+ while (eb_gettag(t) != EB_LEFT)
+ /* Walking up from right branch, so we cannot be below root */
+ t = (eb_root_to_node(eb_untag(t, EB_RGHT)))->node_p;
+
+ /* Note that <t> cannot be NULL at this stage */
+ t = (eb_untag(t, EB_LEFT))->b[EB_RGHT];
+ if (eb_clrtag(t) == NULL)
+ return NULL;
+
+ return eb32sc_walk_down(t, EB_LEFT, scope);
+}
+
+/* Return leftmost node in the tree, or NULL if none */
+static inline struct eb32sc_node *eb32sc_first(struct eb_root *root, unsigned long scope)
+{
+ return eb32sc_walk_down(root->b[0], EB_LEFT, scope);
+}
+
+#endif /* _EB32SC_TREE_H */